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Ansys Learning Forum › Forums › Discuss Simulation › General Mechanical › PSD (acceleration, g^2/Hz) on a body for Random Vibration › Reply To: PSD (acceleration, g^2/Hz) on a body for Random Vibration

September 27, 2024 at 10:48 am
AR
Subscriber

Hello Harshvardhan,

Yes, I have tried changing PSDUNIT,1,PRESS to both PSDUNIT,1,ACEL and PSDUNIT,1,ACCG. Although it does not give me a calculation error, the results I get in the case of ACEL and ACCG. are equal to 0.

I have looked at the Solver Output and the fundamental difference is that for ACEL and ACCG there is no PARTICIPATION FACTORS FOR NODAL EXCITATION, while for PRES there is. (I leave images below).

I have also tried to put CMACEL in the modal, to be able to use the LVSCALE for acceleration. But it does not work either.

Below I leave the two commands. With "!" are the parts that I have used to try to insert the PSD as a g^2/Hz acceleration.
For the Modal:

sf,FACE3,press,1
!CMACEL,FACE3,1

For the Harmonic:

psdunit,1,pres
!psdunit,1,acel
!psdunit,1,accg
lvscale,100! scale pressure from modal
psdfrq,1,1,10,10000! create spectrum table using constant value / change as needed
psdval,1,10,10 ! create spectrum table using constant value / change as needed
pfact,1,node! nodal excitation
!dmprat,.01 ! damping ratio
!psdcom
!solve

 

Could you help me with that?

 

Regards